This invention is in the field of analog to digital encoders and decoders, and more particularly to voice encoders and decoders.
Analog to digital encoders and decoders are well known in the art. The advantages of converting an analog signal to a digital signal for purposes of communication and processing are well known and recognized. Voice signals are analog signals that are quite complex and require a high signal to noise (S/N) ratio and low harmonic and intermodulation distortion and therefore have encoding requirements that many enoders cannot meet.
A particular encoding system that has been used to encode voice signals is known as a continuously variable slope delta (CVSD) modulator. However, even this system has undesirably low S/N ratios and high distortion levels for low intensity input signals, due to digitization and other noise and excessive harmonic and intermodulation distortion.